class code2 {
    //排序数组
    //快排
    //1.分三块
    //2.随机key
    public int[] sortArray(int[] nums) {
        qsort(nums,0,nums.length-1);
        return nums;
    }
    public void qsort(int[] nums,int l,int r) {
        if(l>=r) return;//x在nextInt方法中必须大于0

        int key = nums[new Random().nextInt(r-l+1)+l];
        int left = l-1,right=r+1,i=l;
        while(i<right) {
            if(nums[i]<key) {
                swap(nums,++left,i++);
            } else if(nums[i]==key) {
                i++;
            } else {
                swap(nums,--right,i);
            }
        }
        qsort(nums,l,left);
        qsort(nums,right,r);

    }
    public void swap(int[] nums,int a,int b) {
        int tmp = nums[a];
        nums[a] = nums[b];
        nums[b] = tmp;
    }
}
